assmp...acid sulfate soil - pass) and an acid soil horizon affected by oxidation of sulfides (i.e....

22 July 2015

ABBOT POINT GROWTH GATEWAY PROJECT

Preliminary Acid Sulfate Soil Management Plan

AS

SM

P

Report Number. 1525905-054-R-Rev0

Distribution:

1 x PDF

Submitted to:

Department of State Development

PRELIMINARY ASSMP - ABBOT POINT GROWTH GATEWAY

22 July 2015 Report No. 1525905-054-R-Rev0

Record of Issue

Company Client Contact Version Date Issued Method of Delivery


Project Manager Rev A 16/7/2015 Electronic


Project Manager Rev 0 22/7/2015 Electronic


22 July 2015 Report No. 1525905-054-R-Rev0 i

Table of Contents

1.0 INTRODUCTION ..................................................................................................................................................... 1

2.0 PROJECT OVERVIEW ........................................................................................................................................... 1

3.0 DMCP SITE ............................................................................................................................................................. 2

3.1 Topography................................................................................................................................................ 2

3.2 Geology ..................................................................................................................................................... 2

3.3 Previous Investigations .............................................................................................................................. 2

3.4 Ground Conditions ..................................................................................................................................... 3

3.5 Groundwater .............................................................................................................................................. 3

4.0 DREDGED MATERIALS ........................................................................................................................................ 3

5.0 MITIGATION STRATEGIES AND CONTINGENCY OPTIONS .............................................................................. 4

6.0 MANAGEMENT PROCEDURES ............................................................................................................................ 8

6.1 DMCP Construction ................................................................................................................................... 8

6.2 Dredged Material ....................................................................................................................................... 9

7.0 RESPONSIBILITIES ............................................................................................................................................. 11

8.0 NON-CONFORMANCE AND CORRECTIVE ACTION......................................................................................... 11

9.0 AUDITING ............................................................................................................................................................. 11

10.0 COMMUNITY RELATIONS .................................................................................................................................. 11

11.0 TRAINING ............................................................................................................................................................. 12

12.0 REFERENCES ...................................................................................................................................................... 12

TABLES

Table 1: Summary of mitigation strategies and contingency options based on expected behaviour of ASS Material ...... 5

APPENDICES

Appendix A Acid Sulfate Soil Management Procedures – DMCP

Appendix B Acid Sulfate Soil Management Procedures – Dredged Material

Appendix C Acid Sulfate Soil Management Procedures – Post Dredging


22 July 2015 Report No. 1525905-054-R-Rev0 1

1.0 INTRODUCTION

This Acid Sulfate Soil (ASS) Management Plan (ASSMP) has been developed for the Abbot Point Growth

Gateway Project at the port of Abbot Point, Queensland. The various phases of the project include:

Dredged Material Containment Ponds (DMCP) Construction

Dredging including placement of dredged material in the DMCP and returning seawater back the ocean

Management of dredged material within the ponds post dredging

Management for reuse

Acid Sulfate Soil (ASS) is a general term applying to both a soil horizon that contains sulfides (i.e. Potential

Acid Sulfate Soil - PASS) and an acid soil horizon affected by oxidation of sulfides (i.e. Actual Acid Sulfate

Soil - AASS). ASS may be peats, silts, clays, or sands.

The ASSMP has been based on available soils and water quality investigations previously completed for

offshore works at Abbot Point and the results of recently completed ASS investigations across the DMCP

footprint. The Procedures contained within this ASSMP should be updated and revised to address conditions

encountered that vary from those indicated by investigations or where alternative construction methodologies

are adopted.

The ASSMP was prepared with consideration of the following documents:

Queensland Acid Sulfate Soil Technical Manual: Soil Management Guidelines V4.0, 2014. Dear, S-E.,

Ahern, C. R., O'Brien, L. E., Dobos, S. K., McElnea, A. E., Moore, N. G. & Watling, K. M. Department of

Science, Information Technology, Innovation and the Arts, Queensland Government;

Guidelines for Sampling and Analysis of Lowland Acid Sulfate Soils in Queensland, 1998; Ahern, CR.,

Ahern, M.R. and Powell;

State Planning Policy, July 2014

State Planning Policy – state interest guideline, Water quality, August 2014

Environmental Protection Act 1994; and

Environmental Protection Policy (Water) 2009

The purpose of the ASSMP is to mitigate or control potential impacts relating to:

Earthworks and construction of the proposed DMCP

On-shore placement of dredged material associated with the proposed Terminal 0 (T0) capital dredging

at the port of Abbot Point

2.0 PROJECT OVERVIEW

The proposed capital dredging of approximately 1,100,000 m3 in-situ material for the expansion of T0 at

Abbot Point is expected to result in approximately 2.4 million m3 (bulked volume) of dredged material.

Onshore disposal of dredged material will require the construction of the DMCP to hold the dredged material

and to manage seawater received as part of the dredging process to a standard where it can be returned

back to the ocean in accordance with approval conditions.

The DMCP has a surface area of approximately 630,000 m2 and approximately 5.2 km of perimeter

embankments. The floor of the DMCP will have a surface level of about 2.84 m AHD. The average thickness

of dredged material to be placed across the DMCP is about 4m. It is expected that the DMCP will have an

internal bund dividing the DCMP into a primary and secondary pond to assist in the settlement of sediment.

Dredging discharge will occur into the primary pond resulting in the containment of coarser sediments,

captured fines in the coarse matrix, and clay “balls” whilst finer sediments will be predominantly flushed into

the secondary pond.



Following the completion of dredging the dredged material may be beneficially re-used as part of future port

developments. This may either be by using the material within the T2 site and adjacent industrial land (e.g. to

raise the level of the land), construction over the reclaimed areas or by excavation and reuse of the material

at other locations within the port (e.g. for use as general or construction fill).

3.0 DMCP SITE

3.1 Topography

The proposed DMCP site is bordered by the existing Abbot Point Coal Terminal settlement pond to the north,

beyond which is Bald Hill and then Dingo Beach and the Pacific Ocean. West and south of the site are the

Caley Valley wetlands. The Abbot Point Coal Terminal is to the east.

The majority of the proposed DMCP site is located on a relatively level “terrace” area which is about 1m to

2m higher than the surface levels in the Caley Valley wetlands. From the middle of the site, there is a gentle

slope from the south to the north ranging in elevation from approximately 5.2 m AHD to 3.0 m AHD.

3.2 Geology

The 1:250,000 scale Geological Map of the Ayr region indicates that the site is underlain primarily by

Quaternary coastal dunes and sand plains (Qr) derived primarily from wind action (aeolian). To the south

and south west of the site (Caley Valley Wetland) the geology is comprised of Quaternary age marine

coastal mud flats (Qm) comprising clay, silt, sand, estuarine and deltaic deposits.

Near surface Quaternary aged sediments have been deposited in recent geological time (0 – 2 Myr).

Quaternary materials can be subdivided into recent Holocene materials (<10 kyr) which are typically loose,

or soft normally consolidated materials that are deposited above Pleistocene soils (10 kyr – 2 Myr) which are

stiffer, or denser over consolidated materials. The latter were deposited during sea level conditions which

oscillated around 120 m below present levels.

Sub-types of Quaternary soils may also be classified by their depositional environment such as marine,

estuarine, alluvial or colluvial soils. Other Quaternary aged soils include in-situ residual soils which are a

remnant weathering product derived from the underlying rock.

3.3 Previous Investigations

In 2009, a detailed ASS investigation was undertaken by Aurecon Hatch on behalf of Ports Corporation

Queensland (PCQ) for the Abbot Point Coal Terminal upgrade works (X80/X100 expansion). This

investigation covered portions of and areas adjacent to the current subject site. The investigation was limited

to 4 m below ground level (bgl) at all locations. The findings of the Aurecon Hatch report indicated the

following:

The area had not previously been mapped by QASSIT for AASS or PASS.

Ground conditions across the X80/X100 expansion area generally encountered alluvial sandy clays and

clayey sands interbedded with sands to depths of at least 4 m bgl.

Field pH screening results indicated that AASS were not present under the X80/X100 expansion area

within the samples collected. Field screening results indicated the possible presence of PASS in the soil

profile along the margin of the Caley Valley wetland, generally greater than 3 m below the existing

ground surface. Field screening results did not indicate the possible presence of PASS over the

remainder of the more elevated terrace area.

Soil laboratory results were consistent with the field screening and confirmed the absence of AASS in

the samples analysed, the presence of PASS in the soil profile below 3 m in the soil profile along the

margin of the Caley Valley wetland, and the absence of PASS across the terrace areas to depths of at

least 4 m bgl. Lime neutralisation treatment rates for identified PASS ranged from 1 kg/m3 to >25 kg/m3.



Locations where PASS was identified are situated outside of the proposed DMCP footprint.

The Aurecon Hatch report also referenced an earlier preliminary ASS investigation of the Stage 3 Expansion

by WBM Pty Ltd (WBM) in 2005. The WBM investigation involved sampling to maximum depths of 1.3m at

20 locations and confirmed the absence of PASS over that shallow depth range.

3.4 Ground Conditions

An ASS investigation was undertaken across the proposed DMCP site by Golder between 19 and 24 May

2015). The investigation comprised 25 boreholes to depths of up to 5m depth across the across the footprint

of the pond area including a series of locations spaced at about 100m intervals along the south-western

footprint boundary (i.e., closest to the Caley Valley wetland) where the highest risk of encountering ASS was

expected due to water level fluctuation associated with the wetland.

The results from this investigation confirmed the absence of AASS and PASS within the upper 5m across the

proposed DMCP site. Excavation below this depth is not proposed. The materials to be excavated are

considered suitable for excavation and reuse without ASS restriction / management requirements.

3.5 Groundwater

Six shallow groundwater monitoring wells were installed across the DMCP footprint during recent ASS

investigations by Golder Associates.

Groundwater sampling conducted during the ASS investigation generally indicates a relatively stable and

neutral environment with a high buffering capacity. Test results do not indicate that groundwater has been

affected by historical oxidation of sulphides; although relatively high levels of aluminium and iron were

detected in some groundwater samples. Dewatering groundwater from the DMCP footprint will not be

required to construct the DMCP and therefore monitoring and possible treatment of groundwater is not

required during construction.

4.0 DREDGED MATERIALS

GHD (2012) conducted ASS analysis on samples collected from 69 locations across the proposed T0, T2

and T3 dredging areas. A total of 12 of these locations are within the T0 dredging area (the subject of this

plan) however samples from the adjacent T2 and T3 sites are considered representative of the T0 dredged

material due to their proximity and similarity of soil characteristics.

The GHD (2012) investigation across all the dredging areas were relatively consistent and generally

indicated the following:

Soil profiles across the areas to be dredged is generally comprised of about 2m of marine sediments

(loose/soft sands, clayey sands and sandy clays) overlying alluvial deposits of firm to very stiff sandy

clays.

Laboratory tests on recovered samples indicated that the marine sediments were PASS with a natural

neutralising capacity greater than the acid generating capacity, likely due to the presence of shell and

other calcareous materials throughout the sediment. This suggests that these marine sediments are

“self-neutralising”.

Laboratory tests on recovered samples indicated that the underlying firm to very stiff alluvial deposits

are not acid sulfate soils. ASS management measures are not required for these materials.

GHD (2011) conducted offshore geotechnical investigations for a proposed Multi Cargo Facility (MCF) about

3 km east of the T0 dredging area. This investigation encountered a similar surface layer of marine

sediments and these samples may also be considered representative of the material to be dredged. Again

ASS testing on the marine sediments from the MCF indicated that these were self-neutralising PASS.

Whilst the investigation conducted across the T0 dredging area does not meet spatial requirements of

QASSIT, relatively homogenous conditions (across the T0, T2 and T3 dredging area) were encountered and

the findings are considered to be suitable to develop an ASSMP for the project.



The available ASS investigation results indicate that the marine sediments offshore of Abbot Point are self-

neutralising. The combination of the acid generating potential and the volume of material to be dredged

places this project in the extra high treatment level category (Soil Management Guideline, 2014).

This Preliminary Acid Sulfate Soil Management Plan outlines management measures including additional

sampling and analysis of dredged material and associated water, and describes contingency options to be

considered for neutralisation treatment, if required.

In developing this Preliminary ASSMP the potential for overstated available neutralising capacity has been

considered, including the following:

The marine sediments are saturated and / or have very high moisture contents with saltwater filling the

pore spaces between the soil particles. The saltwater provides some buffering capacity which may

overstate the available neutralising capacity indicated by laboratory tests, in the very long term as the

saltwater will leach out of placed dredge materials.

As part of the laboratory testing process for ASS, samples are dried and ground. If large particles of

shell and coral are not removed prior to grinding, the available neutralising capacity may be overstated

as, in the field, these large particles would develop a gypsum coating in the presence of acid and are

not a fully available neutralising source.

During operation of the DMCP, placement and associated particle size segregation and subsequent remixing

of dredged material will be dependent on the methods and equipment in use by the contractor. This ASSMP

has considered the effects of:

Segregation of dredged material due to the predominantly coarser particles (with minor trapped fines)

dropping out of suspension close to the dredge material discharge location within the primary pond.

These materials may form ‘beaches’ close to the discharge point, with the sediment size tapering to

finer materials away from the discharge.

Shell material is also expected to be deposited non-uniformly due to particle size and density.

The secondary pond is expected to capture the finer particles. It is possible that these fine particles may

not have the same neutralising capacity as indicated from offshore sampling and represent the highest

risk of producing “pockets” of PASS that may generate future unbuffered acidity when dried.

The risk of dredged materials generating acid (should PASS be present) under saturated conditions during

placement is very low as the presence of sufficient oxygen is required to result in acid generation.

5.0 MITIGATION STRATEGIES AND CONTINGENCY OPTIONS

Potential environmental considerations associated with ASS disturbance or onshore placement of dredged

material are summarised in Table 1 below. Also included are proposed management strategies and

contingency options that may be used individually or in combination to mitigate potential impacts if required.



Table 1: Summary of mitigation strategies and contingency options based on expected behaviour of ASS Material

Activity Issue Expected Behaviour of ASS Material Perceived Level of Impact to the Environment

Mitigation Strategies Contingency Options

DMCP Construction

Suspected ASS materials are encountered during DMCP excavation works

No ASS materials or conditions where ASS may be expected have been encountered during investigations across the DMCP footprint.

Negligible to low potential for environmental impact.

Construction inductions to include training on the identification of possible ASS materials.

Testing of possible ASS materials observed during construction.

Lime neutralisation treatment of any confirmed ASS.

Off-shore marine sediments during dredging

Aeration of ASS materials during dredging operations.

Marine sediments which are disturbed during the dredging activities but not recovered for onshore disposal will remain saturated and will not oxidise. Therefore these residual materials will not generate acid and do not represent a risk to the marine environment.

Negligible to low potential for environmental impact.

Water quality monitoring as outlined in separate Dredging Management Plan

Not required

Dredged Material Placement in the DMCP

Acid generation from dredged material and release to soil and groundwater.

Release of acidic and/or metals impacted tailwater through return water outflow.

As dredged material is placed in the DMCP, the dredge contractor will manage supernatant water within the DMCP to maximise settling of suspended sediments to ensure return water quality objectives can be met. Accordingly, the dredged material will generally remain saturated and these saturated conditions represent a low potential for acid generation.

The groundwater investigations indicate that the groundwater in the vicinity of the DMCP is alkaline, contributing to additional buffering capacity.

The active operation of the DMCP during dredging may result in temporarily exposed beaches of coarse dredged material (e.g. in the Primary pond) where PASS, if present, could oxidise and generate acidity. However, the presence of shell material and seawater is expected to continue to provide substantial buffering capacity and would rapidly neutralise this acid, if generated.

Testing to date indicates that the ASS materials to be dredged are “self-neutralising”.

There is a low to moderate potential for these materials to generate excess acidity.

There is a low potential for ASS materials to generate acid during the placement works whilst they remain saturated with sea water.

Low to moderate potential for environmental impact

Laboratory testing of historical vibrocore samples from the Multi Cargo Facility offshore investigations (GHD 2011).

Strategies to be reviewed and updated if self-neutralising ASS is not confirmed.

Lime guard layer to be placed over the base of the secondary pond.

Phased characterisation/verification testing of placed dredged materials, by visual identification, field screening and subsequent laboratory testing, if warranted. Initial focus on fine materials segregated during placement. Strategies to be reviewed and updated if a higher level of risk is indicated.

Groundwater quality monitoring surrounding the ponds.

Tailwater monitoring and management.

Lime dosing during placement or lime treatment post placement.

Treatment of tailwater prior to discharge.





Dredged Material in the DMCP, Post – Dredging


Acid generation from dredged material and release to soil and surface water from the final landform.

The fine particles that settle in the secondary pond may not have the same neutralising capacity as indicated from offshore sampling and represent a potential to produce “pockets” of PASS that may generate future unbuffered acidity when dried

Post-dredging, the dredged material may remain in the DMCP for some time. Over time, the fine dredged material in the secondary pond will be subject to both drainage and surface evaporation, resulting in a caked crust which will crack and provide oxidized conditions around the cracks. Where PASS is present, this can result in acid formation in these exposed materials which may be mobilised by rainfall and require surface runoff to be treated. Deeper materials (at least the bottom 2m) are expected to remain saturated for at least several years and are unlikely to generate acid, where PASS is present, within this time frame.

Post-dredging, where acid is leached through the soil, it can strip heavy metals from the soils and could result in groundwater impacts. The presence of saltwater in the underlying saturated dredge materials will initially contribute to buffering this acid. However, seasonal rainfall and continuous drainage conditions will eventually leach the saltwater from these soils and the buffering capacity will be progressively reduced at rates that are difficult to predict. Additionally, the groundwater beneath the DMCP has significant buffering capacity and is expected to neutralise incidental acid leaching and precipitate metals from solution. It is not intended that saltwater and/or groundwater buffering capacities would be relied upon as the primary neutralisation mechanisms.

Testing to date indicates that the ASS materials to be dredged are “self-neutralising” and groundwater is alkaline. There is a low to moderate potential for these materials to generate excess acidity, varying with time and location within the pond. Oxidised soil that has been “flushed” with rainwater has a higher potential to generate acidity.

Low to moderate potential for environmental impact

Characterisation/verification testing of placed dredged materials.

Lime guard layer to be placed over the base of the secondary pond to address potential acid leaching and to precipitate metals from solution, if acid conditions occur.

Placement of crushed limestone at surface water discharge points and monitoring of water quality at these locations.

Groundwater quality monitoring surrounding the ponds.

In-DMCP treatment by lime addition and mixing

Excavation and treatment within the DMCP; redistribution and mixing

Excavation and treatment external to the DMCP; redistribution and mixing

Limed trench at relevant sections of embankments

Treatment of surface water runoff from the DMCP using lime dosing.





Removal of Dredged Material for Re-use


Future removal of dredged material from the DMCP for reuse will result in aeration of these materials and could result in acid generation from untreated PASS materials, if present, in their final placement location.

Testing to date indicates that the ASS materials to be dredged are “self-neutralising”. There is a low to moderate potential for these materials to generate excess acidity.

Low to moderate potential for environmental impact.

Characterisation/verification testing of placed dredged materials to confirm non-ASS, or treatment of ASS prior to removal, if necessary.

In-DMCP treatment prior to removal.

Adopt management and treatment measures at placement site.



6.0 MANAGEMENT PROCEDURES

The following provides representative management procedures related to phases of activity by use of a

visual summary of the mitigation strategies and contingency options identified for the ASS materials in the

DMCP. These procedures will be reviewed and revised as the project matures and additional information

becomes available.

6.1 DMCP Construction

Flow Chart 1 summarises the mitigation strategies, including contingency options for identified ASS materials

underlying the DMCP.

Flow Chart 1: Summary of DMCP Construction ASS Management

The management procedures and contingency measures to address the unexpected discovery of ASS during DMCP construction are presented in Appendix A.

Possible ASS encountered

during DMCP excavation

No Additional

Management

Required

ASS

Confirmed

Excavation/

disturbance of

Non-ASS

Review and Revise

ASSMP

Identification and

Characterisation of

Possible ASS; Refer

Procedure CP-A

Dewatering of

groundwater

seepage

entering

excavation

Non-ASS

Confirmed

Treatment and

Verification; Refer

Procedure CP-B



6.2 Dredged Material

Flow Chart 2 summarises the mitigation strategies, including contingency options, for dredged materials to

be placed on shore during dredging operations.

Flow Chart 2: Summary of Dredged Material ASS Management

The management procedures and contingency options to address characterisation / verification of dredged ASS are presented in Appendix B.

No Additional Management Required

Dredged Materials

Phased Characterisation /

Verification of placed Materials

Refer to Procedure DS-A

Treatment Required

No

Treatment and verification under

contingency options

Refer Procedure PD-A

Yes

Pond Water & Return Water

Monitoring

Refer Procedure DS-C

Groundwater Monitoring

Refer Procedure DS-D

Incorporation of Lime Guard

Layer in Pond Base Prior to

Placement



6.3 Post Dredged Material Placement/Reuse

Flow Chart 3 summarises the mitigation strategies, including contingency options, for dredged materials post

placement in the DMCP and during reuse, if necessary.

Flow Chart 3: Summary of Post Dredged Material Placement/Reuse Management

The management procedures and contingency options to address post dredging monitoring and management of dredged ASS are presented in Appendix C.

No Additional Management Required

under reuse scenarios

Dredged Materials

Treatment Verified

Yes

Treatment and verification under reuse

scenarios

Refer Procedure PD-B

No

Surface water monitoring,

treatment and discharge

Refer Procedure PD-C

Groundwater Monitoring

Refer Procedure DS-D

Treatment and verification under

contingency options

Refer Procedure PD-A Groundwater Treatment

under contingency options

Refer Procedure PD-D



7.0 RESPONSIBILITIES

This section outlines the responsibilities to manage, document and report on ASS issues for the project.

The Site Manager is responsible for ensuring that all requirements of the ASSMP are met during the

project.

The Site Foreman is responsible for ensuring the strategies and procedures prescribed in the ASSMP

are implemented at the site in accordance with the specified performance criteria.

The Environmental Manager is responsible for reviewing compliance with the ASSMP and development

of actions to address non-conformance.

All other site personnel are responsible for implementing strategies and procedures prescribed in the

ASSMP, as applicable to their work activities.

8.0 NON-CONFORMANCE AND CORRECTIVE ACTION

Any non-conformance to the ASSMP must be addressed as soon as is practical. The personnel responsible

for the non-conformance must be notified immediately for purposes of issuing rectification instructions.

9.0 AUDITING

The Environmental Manager will be responsible for ensuring that an auditing program is implemented for

construction and treatment works. The audit program shall aim to ensure compliance with the ASSMP and

relevant statutory requirements.

The Environmental Manager shall appoint an experienced ASS practitioner to conduct regular auditing of

activities and ASS management measures. Given the expected construction period a weekly, auditing

schedule is recommended. The frequency of these audits may gradually decrease if a high level of

compliance with the ASSMP is evident.

The audit shall take the form of a visual inspection of the works and treatment sites and associated control

measures and a review of monitoring data. A written record of auditing undertaken shall be maintained,

including details on the date of the audit, activities undertaken, observations made and any non-

conformances identified. A copy of the audit report shall be forwarded to the Environmental Manager within 2

days of the audit.

10.0 COMMUNITY RELATIONS

Concerns or complaints raised by the community (or other parties) in relation to ASS will be directed to the

Environmental Manager for action.

The Environmental Manager shall maintain a concern register recording the following information:

1) Details: Name, address and phone number of party raising the concern.

2) Nature of concern: Detail of issue, date of incident, people involved, and location.

3) Action taken or required: Any action proposed or undertaken to address the concern, including time and

date.

4) Response to action: Was the complainant satisfied with the outcome of the actions taken, if not, what

else needs to be done, or is it outside the scope of the development works.

5) Prevention or re-occurrence: What action has been taken by the nominated responsible person to

ensure the problem will not re-occur.



11.0 TRAINING

All equipment operators, supervisors and subcontractors engaged in excavation works shall participate in

induction training for ASS. This training will include basic recognition and identification of ASS, plus an

outline of the requirements of the ASSMP. The Site Foreman shall verify attendance at induction training

prior to commencement of site works.

12.0 REFERENCES

Geotechnical Investigation Report Abbot Point Bulk Coal Terminal X80/X110 Expansion, Ports Corporation

of Queensland, Connell Hatch 2009.

Acid Sulfate Soil Investigation Report and Management Plan Abbot Point Coal Terminal - X80 and X110

Ports Corporation of Queensland, Connell Hatch May 2009.

Abbot Point, Terminals 0, 2 and 3 Capital Dredging Sediment Sampling and Analysis Plan Implementation

Report, GHD July 2012.

Report No. 41-23408-C-RP-003 Rev. 2, North Queensland Bulk Ports Corporation, Abbot Point Multi Cargo

Facility Offshore Geotechnical Investigations, Factual Geotechnical Report, May 2012

Geotechnical Investigation Factual report, Abbot Point Offshore Geotechnical Investigation - Fieldwork

Report, Golder Associates 2012.



Report Signature Page

GOLDER ASSOCIATES PTY LTD

Paul Scells Russell Merz

Principal Environmental Engineer Principal

PKS/SMB/ps

A.B.N. 64 006 107 857

Golder, Golder Associates and the GA globe design are trademarks of Golder Associates Corporation.

j:\des\2015\1525905\correspondence out\1525905-054-r-rev0-preliminary acid sulfate soil management plan.docx



APPENDIX A Acid Sulfate Soil Management Procedures – DMCP

Procedure CP-A: Identification and Characterisation of Possible ASS

Procedure CP-B: Treatment and Verification of Identified ASS

PROCEDURE CP-A Identification and Characterisation of Possible ASS

22 July 2015 Abbot Point Growth Gateway – Preliminary ASSMP Report No. 1525905-054-R-Rev0

CP-A1. GENERAL

The procedure outlined below is provided for the identification and characterisation of possible ASS

materials encountered during DMCP construction works.

CP-A2. OBJECTIVES

Correct identification of ASS materials.

Comply with conditions of licences, permits or other approvals issued for the project.

CP-A3. STATUTORY REQUIREMENTS AND GUIDELINES

1) Queensland Acid Sulfate Soil Technical Manual: Soil Management Guidelines V4.0, 2014. Dear, S-E.,



2) Guidelines for Sampling and Analysis of Lowland Acid Sulfate Soils in Queensland, 1998; Ahern, CR.,


3) Environmental Protection Act 1994;

4) Environmental Protection Policy (Water) 2009

CP-A4. IDENTIFICATION OF ASS

Where suspected ASS is encountered during excavation works, this procedure shall be used to characterise

such materials.

Acid Sulfate Soil (ASS) is a general term applying to both a soil horizon that contains sulfides (i.e. Potential

Acid Sulfate Soil - PASS) and an acid soil horizon affected by oxidation of sulfides (i.e. Actual Acid Sulfate

Soil - AASS). ASS may be peats, silts, clays, or sands.

A suspect PASS material will typically have one or more of these indicators –

Dark coloured soils (particularly dark grey or black soils).

Wet (saturated sand or clay) located below the groundwater table.

Soft clay or loose sand (stiff or very dense materials will not be PASS)

A sulfurous smell e.g. hydrogen sulfide or ‘rotten egg’ gas

A suspect AASS material will typically have one or more of these indicators –

pH of <4.5

Presence of a yellow and/or red mottling (jarosite/iron oxide)

A sulfurous smell e.g. hydrogen sulfide or ‘rotten egg’ gas

Visual examples of PASS and AASS materials are shown on Plates 1 and 2, respectively.



Plate 1 - Potential Acid Sulfate Soils Plate 2 - Actual Acid Sulfate Soils

CP-A5. MANAGEMENT MEASURES

Training – Equipment operators and supervisors shall be trained in the basic recognition of ASS as part

of a site induction presentation. An experienced ASS practitioner shall be appointed to conduct site

inspections and assist in the identification of ASS on an ‘as required’ basis.

Soil Handling – Where possible ASS is encountered, this material must be excavated separately and

segregated from non-ASS materials. An experienced ASS practitioner will attend site to provide additional

guidance on possible ASS on an as required basis.

Field Screening – Where suspected ASS is encountered a field test (pHf and pHfox) shall be

conducted to provide an initial assessment of the materials. Field screening tests shall be conducted at a

minimum rate of one per 100 m3 (or part thereof) and on each suspected material encountered.

If field screening tests show strong indicators of ASS, the suspect materials shall be transported directly to a

treatment area and measures described in Procedure CP-B shall be followed.

If field tests show low or moderate indicators of ASS, then this material shall be excavated and separately

stockpiled within a bunded area until confirmatory tests have been completed.

Confirmatory tests shall comprise sample analysis for the Chromium Suite of tests. Materials returning net

acidity less than 0.03%S shall be removed from the stockpile area and used without further acid sulfate

management. Where net acidity greater than 0.03%S is found, the materials shall be transported directly to a

treatment area and measures described in Procedure CP-B shall be followed.

Guidance on interpreting Field Screening Tests is provided below:

A pHF of less than 4 is likely to indicate the presence of AASS.

A combination of three indicators is considered in arriving at a ‘positive field sulfide identification’ (i.e. the

presence of PASS):

A reaction with hydrogen peroxide - the strength of the reaction with peroxide is a useful indicator but

cannot be used alone. Organic matter, coffee rock and other soil constituents such as manganese

oxides can also cause a reaction. Care should be exercised in interpreting a reaction on surface soils

and high organic matter soils such as peats and coffee rock and some mangrove/estuarine muds and



marine clays. This reaction should be rated, e.g. L = Low reaction, M = Medium reaction, H = High

reaction, X = Extreme reaction, V = volcanic reaction.

The actual value of pHFOX. - If pHFOX <3, and a significant reaction occurred, then it strongly indicates a

PASS. The more the pHFOX drops below 3, the more positive the presence of inorganic sulfides.

A much lower pHFOX than field pHF - The lower the final pHFOX value and the greater the difference

between the pHFOX compared to the pHF, the more indicative of the presence of PASS. This difference

may not be as great if starting with an already very acid pHF (close to 4), but if the starting pH is neutral

or alkaline then a larger change in pH should be expected. Where fine shell, coral or carbonate is

present the change in pH may not be as large due to buffering. The ‘fizz test’ (effervescence with 1 M

HCl) should be used to test for carbonates and shell.

Of these three factors, the final pHFOX value is the most conclusive. The following interpretation shall be

adopted for field screening tests:

Strong Indicator of PASS – All three indicators present (pHFOX<3; M to H reaction, pHF - pHFOX>3)

Moderate Indicator of PASS – pHFOX>3 and the remaining two indicators are positive

Low Indicator of PASS – pHFOX>3 and one or none of the remaining indicators are positive

CP-A6. MONITORING AND REPORTING

The Site Foreman or their delegated representative shall keep a record of all equipment operators and

supervisors who are trained in the basic recognition of ASS as part of induction training.

The Site Foreman shall maintain a register of test results and a record of inspections.

PROCEDURE CP-B Treatment and Verification of Identified ASS


CP-B1. GENERAL

The procedures outlined below are provided as a contingency measure for the on-site treatment and

verification of ASS materials, if identified during DMCP construction.

CP-B2. OBJECTIVES

Appropriately treat and manage excavated ASS materials so as to minimise adverse effects on the

natural and built environment (including infrastructure).


CP-B3. STATUTORY REQUIREMENTS AND GUIDELINES








CP-B4. TREATMENT MEASURES

CP-B4 (a) Stockpiling of Identified ASS

Stockpiling and treatment of excavated ASS materials shall only be conducted within the site of works of the

DMCP.

CP-B4 (b) Treatment Facility

A treatment facility shall be constructed within the DMCP area in general accordance with the requirement

detailed in Soil Management Guidelines, 2014 (refer Figure CP-B1) and the following additional

requirements:

The treatment area shall be prepared by stripping vegetation, topsoil and soil containing significant

amounts of organic material and compacting the surface with a smooth drum roller. An area of at least

2 m width shall be left between the treatment areas and bunds to allow collection of runoff and direction

to sumps.

A guard layer of fine ground agricultural lime shall be applied to the treatment areas prior to placement

of soils at a rate 5 kg/m2 for each 1m height of soil to be treated.

The treatment facility shall be inspected on a daily basis and maintained to prevent escape of soils or water

from the facility.



Figure CP-B1: Schematic cross-section of a treatment pad, including a compacted clay layer, guard layer, leachate collection system and containment with bund

Excavated ASS materials shall be placed into appropriately identified treatment lots at the treatment facility

where the material shall be spread in layers and allowed to dry (if required).

The overall layer thickness shall not exceed 250 mm thickness unless effective treatment over a greater

thickness can be demonstrated. Where required, drying shall be enhanced by mechanical methods (rotary

hoe, disc plough, etc.) to create a relatively homogenous, friable material prior to addition of lime for

neutralisation.

Fine ground agricultural lime (or other approved neutralising agent) shall be applied to the ASS surface in

each treatment lot using a spreader truck or other approved method. Following lime application, the lime

shall be mixed into the ASS layer using mechanical methods (disc plough, rotary hoe, etc.).

CP-B4 (c) Liming Rates

The liming rates as determined from testing during Procedure CP-A can be adopted for treatment of

confirmed ASS. The highest indicated rate shall apply to a treatment lot.

CP-B4 (d) Verification Testing

Verification samples shall be collected for each treated lot (1 per lot). The samples shall be formed by

compositing materials from three randomly selected locations across the allotment. Samples shall be

collected over the full thickness of the treated lot. The Chromium Suite shall be conducted on each sample

to confirm net acidity by Acid Base Accounting.

CP-B5. PERFORMANCE CRITERIA

To confirm adequate lime treatment, laboratory testing must demonstrate the following:

A neutralising capacity of more than 1.5 times the sum of existing plus potential acidity, all measured in

the same units (and using a minimum safety factor of 1.5).

Some individual samples may vary from these criteria, as outlined below:

No single sample shall exceed a net acidity of 18 mol H+/tonne (0.03% S); and

If any single sample has a net acidity between 0 and 18 mol H+/tonne (0.00 to 0.03% S), then the

average of any four spatially adjacent samples (including the exceeding sample) shall have an average

net acidity of zero or less.

CP-B6. CONTINGENCY MEASURES

Additional lime treatment and further verification testing shall be conducted where adequate neutralisation is

not initially indicated.



CP-B7. PERFORMANCE INDICATORS

Item Performance Indicator

Earthworks strategy An appropriate earthworks strategy has been prepared to track the treatment

of ASS (appended to the ASSMP)

ASS treatment Treatment procedure employed is in accordance with section CP-A4

Liming rates Correct liming rates are applied for each treatment lot.

Treatment verification

Verification of treatment on each of treated material.

Correct verification laboratory analysis used.

If verification shows performance criteria in section DS-A5 are not met,

additional treatment has been employed.

Non conformance All non-conformances are reported and rectified.

CP-B8. MONITORING AND REPORTING

Records shall be kept to track excavated materials identified as ASS, volumes transported to the treatment

facility, treatment rates applied. The Site Foreman shall conduct an inspection of the treatment areas

including bunds and sumps on a weekly basis.

The Site Foreman shall be responsible for ensuring lime neutralisation and verification tests are completed

for each lot of excavated ASS.

The Site Foreman shall maintain a register of testing results and a record of inspections.

A summary report of all test results and inspections shall be complied by the Site Foreman each week and

submitted to the Environmental Manager.



APPENDIX B Acid Sulfate Soil Management Procedures – Dredged Material

Procedure DS-A: Characterisation and Verification of Dredged Materials

Procedure DS-B: Treatment and Verification of Dredged ASS

Procedure DS-C: Groundwater Quality Monitoring

PROCEDURE DS-A Characterisation and Verification of Dredged Materials


DS-A1. GENERAL

The procedure outlined below is provided to further characterise dredged materials (identified self-

neutralizing ASS) placed in the DMCP during and post placement and to confirm they are self-neutralising.

DS-A2. OBJECTIVES

1) Implement a phased process from field screening to laboratory testing, as required to appropriately

characterise dredged materials to confirm whether treatment is needed or whether the material is self-

neutralising.

2) Comply with conditions of licences, permits or other approvals issued for the project.

DS-A3. STATUTORY REQUIREMENTS AND GUIDELINES








DS-A4. MANAGEMENT MEASURES

As phased approach will be undertaken:, such that if indicate

Visual identification and field screening of samples across the DMCP during placement.

If field screening indicates, samples of finer materials deposited in the secondary pond will be collected

early in the placement works using a long arm excavator, using a piston sampler from a punt/boat, or

other suitable method. These samples will be analysed for the Chromium Suite of tests to evaluate if

other than self-neutralising materials (i.e. PASS) is being deposited.

Kinetic tests (column leaching tests) using fresh water will be conducted on these samples of finer

materials deposited in the secondary pond from early in the placement works to confirm the potential for

longer term risk associated with storing these materials in the DMCP.

Based on field screening results, an earthworks strategy may be developed to spatially identify the

locations of appropriately sized “lots” of placed dredged materials. Samples of the dredged material

shall be collected on a 1 per lot basis. It is expected that the coarser materials in the primary pond

should be accessible by foot or light equipment to enable sampling. In areas where finer materials are

present sampling using a piston sampler from a punt/boat or other suitable sampling methods will be

employed to collected characterisation/verification samples. Characterisation/verification samples will

be analysed using the Chromium Suite of tests, following removal of shells and shell fragments larger

than 2 mm.

DS-A5. PERFORMANCE CRITERIA

To confirm dredged materials as self-neutralising ASS materials or non-ASS, laboratory testing must

demonstrate one of the following:

Sum of existing plus potential acidity (excluding neutralising capacity) of less than 18 mol H+/tonne

(0.03% S); or



PROCEDURE DS-A Characterisation and Verification of Dredged Materials







DS-A6. CONTINGENCY MEASURES

Where the performance criterion is exceeded, the lot represented by the sample shall be lime treated as

outlined in Procedure PD-A.

DS-A7. MONITORING AND REPORTING

Records shall be kept by the Site Manager or their delegated representative to verify volumes of sampling.

Specific records of volumes, origin, material type and placement, including photos, shall be maintained by

the Site Manager or their delegated representative.

The Site Manager or their delegated representative shall develop the materials tracking register plan and

maintain a register of test results.

PROCEDURE DS-B DMCP Water and Return Water Management and Monitoring


DS-B1. GENERAL

The procedures outlined below are provided to monitor pond water quality for discharge to the environment

during dredging works. Management and monitoring relates to ASS indicators only. Reference should be

made to the project Environmental Management Plan for other water quality parameters that may need to be

managed and monitored.

DS-B2. OBJECTIVES

Appropriately monitor waters within the DMCP for ASS parameters.

Appropriately manage, monitor and treat (if required) waters to be discharged from the DMCP.


DS-B3. STATUTORY REQUIREMENTS AND GUIDELINES

1) State Planning Policy – state interest guideline, Water quality, August 2014;





4) Environmental Protection Policy (Water) 2009.

DS-B4. IMPLEMENTATION MEASURES

DS-B4 (a) Monitoring of Water in DMCP

Water within the DMCP shall be monitored prior to discharge.

Where pH is within the range of 6.5 and 8.5 pH measurements shall be conducted using a calibrated meter

twice daily at each nominated monitoring location, when water is present.

Where pH is below 6.5 is detected, continuous pH measurement shall be conducted using a calibrated meter

and datalogger at each nominated monitoring location,

Where pH of less than 5.5 is detected, the water shall be treated by addition of hydrated lime and/or liquid

caustic to achieve a pH of between 6.5 and 8.5. Inline pH adjustment pumps are to be utilized for treatment

of low pH waters (<pH 5.5) prior to discharge.

DS-B4 (b) Discharge to Surface Water Bodies

Return from the DMCP shall be discharged to the ocean via the return water pipeline.

Prior to discharge from the DMCP, water must meet the criteria performance criteria listed in Section DS-B5.

Waters not meeting required performance criteria shall be treated until these criteria are met.

Treatment shall not be permitted as part of direct discharge.

The pH and turbidity (presence of iron floc) in the DMCP return water inlet shall be monitored during

discharge events.

Discharge shall be ceased immediately on discovery of non-conformance with performance criteria.

An appropriate supply of hydrated lime and/or liquid caustic shall be kept on site at all times for the

treatment of acidic waters. Neutralising agents shall be stored in a covered and bunded area to prevent

accidental release to waters.

All monitoring of water quality shall be carried out by a suitably qualified person, using calibrated

equipment on samples that are representative of the discharge or background.

PROCEDURE DS-B DMCP Water and Return Water Management and Monitoring


The Project Environmental Management Plan should also be consulted for guidance on additional

monitoring parameters and performance limits not directly related to ASS.

DS-B5. PERFORMANCE CRITERIA

The State Planning Policy lists the following as acceptable outcomes in relation to ASS and disposal of

wastewater to waterways

i) the pH of any wastewater discharged is maintained between 6.5 and 8.5 to avoid mobilisation of acid,

iron, aluminium, and metals, and

ii) holding times of neutralised wastewaters ensures the flocculation and removal of any dissolved iron

prior to release, and

iii) visible iron floc is not present in any discharge, and

iv) precipitated iron floc is contained and disposed of, and

v) wastewater and precipitates that cannot be contained and treated for discharge on site are removed

and disposed of through trade waste or another lawful method.

In addition to the above, if the pH drops below 5 at any time then this Procedure will need to be reviewed

and the monitoring parameters will be increased to include, total acidity, total alkalinity, ferrous iron and

aluminium.

DS-B6. PERFORMANCE INDICATORS


1. Water Treatment

Systems

Treatment systems maintained and operated according to manufacturer’s

specifications.

2. Water Quality No uncontrolled releases of water from the site. Water discharge within

performance indicators in Section DS-B5.

3. Non conformance All non-conformances are reported and rectified.

DS-B7. MONITORING AND REPORTING

The Site Foreman shall be responsible for ensuring monitoring is conducted at the required frequency.


A summary report of all test results and inspections shall be compiled by the Site Foreman each week and


The Site Foreman shall inform the Environmental Manager of non-compliance upon detection. The

Environmental Manager shall inform EHP of such non-compliances as soon as practicable and instigate an

assessment of the impact.

PROCEDURE DS-C Groundwater Quality Monitoring


DS-C1. GENERAL

The procedure outlined below is provided to monitor groundwater quality around the DMCP during and post

placement of dredge materials.

DS-C2. OBJECTIVES

Appropriately monitor groundwater to identify water quality changes that may indicate ASS impact.


DS-C3. STATUTORY REQUIREMENTS AND GUIDELINES







DS-C4. IMPLEMENTATION MEASURES

A series of monitoring wells shall be installed external to the DMCP and prior to the commencement of any

ground disturbance works to construct the DMCP. The number and location of these monitoring wells will be

confirmed following completion of the groundwater assessment reporting.

The following groundwater monitoring program shall be adopted:

Baseline groundwater quality data shall be collected before the construction of the DMCP. This shall

comprise at least 2 monitoring events of

Field measurements of pH, redox potential (Eh or ORP), dissolved oxygen, standing water level,

electrical conductivity (EC), total titratable acidity and total alkalinity.

Laboratory measurements chloride, sulfate, dissolved aluminium (filtered), dissolved arsenic

(filtered) and dissolved iron (filtered).

During dredging works monitoring of groundwater shall comprise:

Water level, pH and EC (field readings) every second day.

Post construction monitoring shall comprise:

Weekly water table level, pH, EC for at least 6 months following completion of dredging. Extension

of the monitoring program beyond this and final parameters will be determined by a suitably

qualified Environmental Consultant following review of these results.

Performance indicators and response actions for water quality in groundwater wells are listed in DS-C5.

Contingency options to groundwater treatment are discussed in Procedure PD-D.

PROCEDURE DS-C Groundwater Quality Monitoring


DS-C5. PERFORMANCE CRITERIA

Parameter Monitoring Frequency Performance Indicator

Action (after performance indicator

exceedance)

Fie

ld M

eas

ure

men

t

Water Level Every 2nd Day

(during

construction

and dredge

placement)

Every week for

6 months post

(dredging)

- All results to be reviewed

by Environmental

Consultant to confirm the

level of risk and need for

control measures.

pH >5.5 pH (and less than 0.5 pH

drop below baseline)

redox potential -

EC -

DO -

total titratable acidity -

total alkalinity -

DS-C6. MONITORING AND REPORTING

The Site Foreman shall be responsible for ensuring monitoring listed in Section DS-C4 is conducted at the

required frequency.




The Site Foreman shall inform the Environmental Manager of non-compliance with performance criteria upon

detection. The Environmental Manager shall instigate an assessment of the impact within 2 days of such

detections.

A groundwater monitoring report shall be prepared for the Environmental Manager by suitably qualified

Environmental Consultant 6 months after completion of dredge spoil placement. The report shall include

assessment of the results and recommendations for termination or continuation of the monitoring program.

The report shall be submitted to EHP.



APPENDIX C Acid Sulfate Soil Management Procedures – Post Dredging

Procedure PD-A: Treatment and Verification of Dredged ASS

Procedure PD-B: Treatment and Verification for Material Reuse

Procedure PD-C: Post Dredging Surface Water Monitoring

Procedure PD-D: Contingency Options for Groundwater Treatment

PROCEDURE PD-A Treatment and Verification of Dredged ASS


PD-A1. GENERAL

The procedures outlined below provide contingency options for on-site treatment and verification of placed

dredged material, confirmed as not self-neutralising ASS. This procedure should be reviewed and revised

should other treatment options be considered.

PD-A2. OBJECTIVES

Appropriately treat and manage ASS materials so as to minimise adverse effects on the natural and built environment (including infrastructure).


PD-A3. STATUTORY REQUIREMENTS AND GUIDELINES








PD-A4. TREATMENT OPTIONS

PD-A4 (a) In-line Dosing

Where initial testing of fine grained material in the secondary pond (Procedure DS-A) indicates ASS with

insufficient self-neutralising capacity, in-line application of additional neutralising agents may be trialled to

negate the need for other in-DMCP or ex-DMCP treatment. A low soluble neutralising agent will need to be

adopted.

PD-A4 (b) Earthwork Strategy

An earthworks strategy shall be developed to plan and track movement, treatment and verification of each

appropriately sized “lot” of ASS material, where self-neutralisation performance criteria are not met.

PD-A4 (c) In-DMCP Treatment

Where conditions permit, it is preferable for treatment of ASS materials to be conducted within the DMCP.

Shallow (0-0.5 m from surface) treatment – Where ASS is indicated in near surface soils within a characterised earthworks “lot”, lime or other neutralising agent may be applied directly to the drained surface to provide a buffering source. In areas of coarser material that are accessible on foot or using light equipment, the neutralising agent should be incorporated into the surface layer by mechanical methods (rotary hoe, disc plough, excavator bucket etc.).

Deep (0.5-4 m from surface) treatment – Deeper materials maybe reworked using a small slurry pump to mix lime/neutralising agent into the material. This could be conducted within the existing DMCP. A material tracking and verification testing as outlined in Procedure DS-A would be required. Alternatively, neutralising agent injection and soil mixing could be undertaken with mechanical mixing methods (e.g. excavator bucket mixing, jet grouting and shallow soil mixing equipment, cutter soil mixer, etc.).

Consideration may be given to mixing of course material within the DMCP with either fines and/or silty sand material stockpiled from construction of the DMCP.



PD-A4 (d) Ex-DMCP Treatment Facility

Where identified ASS cannot be feasibly spread and treated within the DMCP, an ex-DMCP treatment facility

shall be constructed in general accordance with the requirement detailed in Soil Management Guidelines,

2014 (refer Figure PD-A1) and the following additional requirements:

Treatment areas shall be located at least 30 m from the banks of waterways.


amounts of organic material and compacting the surface with a smooth drum roller. If sandy materials

are exposed in the stripped surface, a layer of low permeability material shall be placed over the

stripped surface (compacted clay or other acceptable low permeability material). An area of at least 2 m

width shall be left between the treatment areas and bunds to allow collection of runoff and direction to

sumps.

Treatment pads shall be contained within a bunded area. Bund walls shall be constructed with clean

material approved by the Supervisor (i.e. not ASS or acidic soils). Bund walls should be a minimum of

0.5 m in height.



The treatment facility and bund walls shall be inspected on a daily basis and maintained to prevent escape of

soils or water from the facility. Where feasible, the layers of treated and verified material may be compacted

in place to progressively build a final fill platform for development use.

Figure PD-A1: Schematic cross-section of a treatment pad, including a compacted clay layer, guard layer, leachate collection system and containment with bund

ASS materials shall be placed into identified treatment lots at the treatment facility where the material shall

be spread in layers and allowed to dry (if required).




neutralisation.




Calculations for determining appropriate liming rates are provided in Section PD-A4(e)



PD-A4 (e) Liming Rates

Lime neutralisation rates for each treatment lot shall be determined from the initial characterisation result.

The liming rate required to neutralise the Net Acidity (Existing Acidity + Potential Acidity) shall be calculated

by:

Multiplying Net Acidity by a safety factor of 1.5 to allow for mixing deficiencies and poor reactivity of the

lime;

Multiplying the above result by the bulk density of the soil to arrive at the liming rate (kg/m3).

Multiplying the above result by 1.03 (to account for an agricultural lime neutralising value of 97%).

Calculating surface application rate (kg/m2) by multiplying the above result by the thickness of soil

being treated.

PD-A4 (f) Verification Testing

Verification samples shall be collected for each treated lot. The samples shall be formed by compositing

materials from three randomly selected locations across the allotment. Samples shall be collected over the

full thickness of the treated lot. The Chromium Suite shall be conducted on each sample to confirm net

acidity by Acid Base Accounting.

PD-A5. PERFORMANCE CRITERIA









PD-A6. CONTINGENCY MEASURES


not initially indicated. Alternatively, where it can be demonstrated that the residual risk can be managed

within the DMCP, residual lime treatment can be conducted as part of future material removal/reuse.

PD-A7. PERFORMANCE INDICATORS




ASS treatment Treatment procedures employed



Verification of treatment on each lot of treated material.


If verification shows performance criteria in section PD-A5 are not met,





PD-A8. MONITORING AND REPORTING

Records shall be kept to verify volumes of soils treated. Where exsitu treatment is conducted records shall

be kept of volumes transported to the treatment facility. The Site Foreman shall conduct an inspection of the

treatment areas including bunds and sumps on a weekly basis.


for each lot of ASS.




PROCEDURE PD-B Treatment and Verification for Material Reuse


PD-B1. GENERAL

The procedures outlined below are provided as contingency measures for the treatment and verification of

dredged materials confirmed as not self-neutralising ASS but not adequately treated in the DMCP prior to

reuse.

PD-B2. OBJECTIVES

Appropriately treat and manage ASS materials so as to minimise adverse effects on the natural and built environment (including infrastructure).


PD-B3. STATUTORY REQUIREMENTS AND GUIDELINES








PD-B4. TREATMENT MEASURES

In addition to lime neutralisation, consideration may be given to mixing of course dredged material with fine

dredged material and/or silty sand material stockpiled from construction of the DMCP.

PD-B4 (a) Treatment Facility

Where identified ASS cannot be feasibly spread and treated within the dredge ponds an ex-DMCP treatment

facility shall be constructed in general accordance with the requirement detailed in Soil Management

Guidelines, 2014 (refer Figure PD-B1) and the following additional requirements:

Treatment areas shall be located at least 30m from the banks of waterways.


amounts of organic material and compacting the surface with a smooth drum roller. If sandy materials

are exposed in the stripped surface, a layer of low permeability material (compacted clay or other

acceptable low permeability material) shall be placed over the stripped surface. An area of at least 2m

width shall be left between the treatment areas and bunds to allow collection of runoff and direction to

sumps.

Treatment pads shall be contained within a bunded area. Bund walls shall be constructed with clean

material approved by the Supervisor (i.e. not ASS or acidic soils). Bund walls should be a minimum of

0.5m in height.



The treatment facility and bund walls shall be inspected on a daily basis and maintained to prevent escape of

soils or water from the facility. Where feasible, the layers of treated and verified material may be compacted

in place to progressively build a final fill platform for development use.



Figure PD-B1: Schematic cross-section of a treatment pad, including a compacted clay layer, guard layer, leachate collection system and containment with bund

ASS materials shall be placed into identified treatment lots at the treatment facility where the material shall

be spread in layers and allowed to dry (if required).




neutralisation.




Calculations for determining appropriate liming rates are provided in Section PD-B4(b)

PD-B4 (b) Liming Rates

Lime neutralisation rates for each treatment lot shall be determined from the initial characterisation result.

The liming rate required to neutralise the Net Acidity (Existing Acidity + Potential Acidity) shall be calculated

by:

Multiplying Net Acidity by a safety factor of 1.5 to allow for mixing deficiencies and poor reactivity of the

lime;

Multiplying the above result by the bulk density of the soil to arrive at the liming rate (kg/m3).

Multiplying the above result by 1.03 (to account for an agricultural lime neutralising value of 97%).

Calculating surface application rate (kg/m2) by multiplying the above result by the thickness of soil

being treated.

PD-B4 (c) Verification Testing

Verification samples shall be collected for each treated lot. The samples shall be formed by compositing

materials from three randomly selected locations across the allotment. Samples shall be collected over the

full thickness of the treated lot. The Chromium Suite shall be conducted on each sample to confirm net

acidity by Acid Base Accounting.

PD-B5. PERFORMANCE CRITERIA











PD-B6. CONTINGENCY MEASURES


not initially indicated.

PD-B7. PERFORMANCE INDICATORS




ASS treatment Treatment procedures employed



Verification of treatment on each lot of treated material.


If verification shows performance criteria in section PD-B5 are not met,



PD-B8. MONITORING AND REPORTING

Records shall be kept to verify volumes of soils treated and the volumes transported to the treatment facility.

The Site Foreman shall conduct an inspection of the treatment areas including bunds and sumps on a

weekly basis.


for each lot of ASS.




PROCEDURE PD-C Post Dredging Surface Water Monitoring


PD-C1. GENERAL

The procedures outlined below are provided to monitor surface water quality and discharge to the

environment during post dredging works. Management and monitoring relates to ASS indicators only.

Reference should be made to the project Environmental Management Plan for other water quality

parameters that may need to be managed and monitored.

PD-C2. OBJECTIVES

Appropriately monitor waters within the DMCP for ASS parameters.

Appropriately manage, monitor and treat (if required) waters to be discharged from the DMCP.


PD-C3. STATUTORY REQUIREMENTS AND GUIDELINES







PD-C4. IMPLEMENTATION OPTIONS

PD-C4 (a) Post Dredging Works

Following completion of the dredging works, the water in the DCMP will be drawn down and additional

discharge points will be formed within the DCMP walls to allow for a maximum freeboard of 0.5m over the

placed dredged materials following a rainfall event.

The discharge points shall be lined with crushed limestone placed to address minor acidity in runoff.

This limestone should be inspected at least every 6 months to check for coating formation and confirm

whether additional or replacement limestone is required.

PD-C4 (b) Discharge to Surface Water Bodies

Monitoring of all discharge points should be conducted; water must meet the criteria performance criteria

listed in Section PD-C5.

Waters not meeting required performance criteria shall be treated until these criteria are met.

Treatment shall not be permitted as part of direct discharge to an external surface water body.

The pH and turbidity (presence of iron floc) in the polishing pond shall be monitored every two hours

during discharge events.

Discharge to surface water bodies shall be ceased immediately on discovery of non-conformance with

performance criteria.

A supply of hydrated lime and/or liquid caustic shall be kept on site at all times for the treatment of

acidic waters. The supply shall be at least 0.5 tonne of hydrated lime and/or 200L of liquid caustic.

Neutralising agents shall be stored in a covered and bunded area to prevent accidental release to

waters.

All monitoring of water quality shall be carried out by a suitably qualified person, using calibrated

equipment on samples that are representative of the discharge or background.

PROCEDURE PD-C Post Dredging Surface Water Monitoring


The Project Environmental Management Plan should also be consulted for guidance on additional

monitoring parameters and performance limits not directly related to ASS.

PD-C5. PERFORMANCE CRITERIA

The State Planning Policy lists the following as acceptable outcomes in relation to ASS and disposal of

wastewater to waterways

i) the pH of any wastewater discharged is maintained between 6.5 and 8.5 to avoid mobilisation of acid,

iron, aluminium, and metals, and

ii) holding times of neutralised wastewaters ensures the flocculation and removal of any dissolved iron

prior to release, and

iii) visible iron floc is not present in any discharge, and

iv) precipitated iron floc is contained and disposed of, and

v) wastewater and precipitates that cannot be contained and treated for discharge on site are removed

and disposed of through trade waste or another lawful method.

In addition to the above, if the pH drops below 5 at any time then this Procedure will need to be reviewed

and the monitoring parameters will be increased to include, total acidity, total alkalinity, ferrous iron and

aluminium.

PD-C6. PERFORMANCE INDICATORS


4. Water Treatment

Systems

Treatment systems maintained and operated according to manufacturer’s

specifications.

5. Water Quality No uncontrolled releases of water from the site. Water discharge within

performance indicators in Section PD-C5.

6. Non conformance All non-conformances are reported and rectified.

PD-C7. MONITORING AND REPORTING

The Site Foreman shall be responsible for ensuring monitoring is conducted at the required frequency.




The Site Foreman shall inform the Environmental Manager of non-compliance upon detection. The

Environmental Manager shall inform EHP of such non-compliances as soon as practicable and instigate an

assessment of the impact.

PROCEDURE PD-D Contingency Options for Groundwater Treatment


PD-D1. GENERAL

The procedures outlined below are provided at this time as a contingency measure to mitigate acidity if

detected during groundwater monitoring.

This procedure may be reviewed and revised following further chemical analysis of the groundwater.

PD-D2. OBJECTIVES

Appropriately capture and/or treat mobilised acidity if detected in the groundwater table.


PD-D3. STATUTORY REQUIREMENTS AND GUIDELINES







PD-D4. IMPLEMENTATION OPTIONS

Contingency options to mitigate mobilised acidity, if detected in groundwater, include one or a combination of

the following:

PD-D4 (a) Cut-off Wall

A cut-off wall may be constructed along selected down-gradient alignments of the DMCP to capture and

contain groundwater beneath the containment pond. The cut-off walls will be designed to restrict

groundwater movement by extending the flow path or extend to a low permeable “confining” below the near

surface water bearing layer.

PD-D4 (b) Lime Trench/PRB

A lime trench or permeable reactive barrier (PRB) could be constructed across major groundwater flow

pathway(s) down-gradient of the DMCP to protect sensitive areas. The lime trench or PRB will be designed

to reduce acid water or movement of metals.

PD-D4 (b) Lime Injection

Line injection could be implemented along the major groundwater flow pathway(s) down-gradient of the

DMCP to protect sensitive areas.

PD-D5. PERFORMANCE CRITERIA

Groundwater monitoring as per Procedure DS-D shall be adopted to monitor performance of the

implementation measures adopted.

PD-D6. CONTINGENCY MEASURES

Where performance criteria are exceeded an experienced Environmental Consultant shall be engaged to

confirm the level of risk and need for additional control measures.

PROCEDURE PD-D Contingency Options for Groundwater Treatment


PD-D7. PERFORMANCE INDICATORS


Contingency Option

Design Design and construction certified by RPEQ

Groundwater

monitoring pH >5.5 (and less than 0.5 pH drop below baseline)


PD-D8. MONITORING AND REPORTING

Design and construction of contingency measures shall be monitored by an RPEQ. Photographic records

shall be kept of construction activities.


A construction report by an RPEQ shall be provided to the Site Foreman.

Golder Associates Pty Ltd

147 Coronation Drive

Milton, Queensland 4064

Australia

T: +61 7 3721 54008943 0689

Caption Text

assmp...acid sulfate soil - pass) and an acid soil horizon affected by oxidation of sulfides (i.e....

Documents